#!/bin/bash

# -------------------------------------------------------------------------- #
# Copyright 2002-2016, OpenNebula Project, OpenNebula Systems                #
#                                                                            #
# Licensed under the Apache License, Version 2.0 (the "License"); you may    #
# not use this file except in compliance with the License. You may obtain    #
# a copy of the License at                                                   #
#                                                                            #
# http://www.apache.org/licenses/LICENSE-2.0                                 #
#                                                                            #
# Unless required by applicable law or agreed to in writing, software        #
# distributed under the License is distributed on an "AS IS" BASIS,          #
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   #
# See the License for the specific language governing permissions and        #
# limitations under the License.                                             #
#--------------------------------------------------------------------------- #

# snap_create host:parent_image snap_id vmid ds_id

SRC=$1
SNAP_ID=$2
VMID=$3
DSID=$4

if [ -z "${ONE_LOCATION}" ]; then
    TMCOMMON=/var/lib/one/remotes/tm/tm_common.sh
    DATASTORES=/var/lib/one/datastores
else
    TMCOMMON=$ONE_LOCATION/var/remotes/tm/tm_common.sh
    DATASTORES=$ONE_LOCATION/var/datastores
fi

DRIVER_PATH=$(dirname $0)

source $TMCOMMON
source ${DRIVER_PATH}/../../vmm/kvm/kvmrc

SRC_PATH=$(arg_path $SRC)
SRC_HOST=$(arg_host $SRC)

#-------------------------------------------------------------------------------
# Get Image information
#-------------------------------------------------------------------------------

DISK_ID=$(basename ${SRC} | cut -d. -f2)

XPATH="${DRIVER_PATH}/../../datastore/xpath.rb --stdin"

unset i j XPATH_ELEMENTS

while IFS= read -r -d '' element; do
    XPATH_ELEMENTS[i++]="$element"
done < <(onevm show -x $VMID| $XPATH \
                    /VM/TEMPLATE/DISK[DISK_ID=$DISK_ID]/SOURCE \
                    /VM/TEMPLATE/DISK[DISK_ID=$DISK_ID]/CLONE \
                    /VM/TEMPLATE/DISK[DISK_ID=$DISK_ID]/TARGET \
                    /VM/DEPLOY_ID \
                    '%m%/VM/TEMPLATE/DISK/TARGET')

DISK_SRC="${XPATH_ELEMENTS[j++]}"
CLONE="${XPATH_ELEMENTS[j++]}"
TARGET="${XPATH_ELEMENTS[j++]}"
DEPLOY_ID="${XPATH_ELEMENTS[j++]}"
ALL_DISKS="${XPATH_ELEMENTS[j++]}"

SYSTEM_DS_PATH=$(dirname ${SRC_PATH})

SYSTEM_DS_DISK_PATH="${SYSTEM_DS_PATH}/disk.${DISK_ID}"
SYSTEM_DS_DISK_PATH_SHORT="disk.${DISK_ID}"

if [ "$CLONE" = "YES" ]; then
    DISK_PATH="${SYSTEM_DS_DISK_PATH}"
    DISK_PATH_SHORT="$(basename ${SYSTEM_DS_DISK_PATH})"
else
    DISK_PATH=$DISK_SRC
    DISK_PATH_SHORT=$DISK_PATH
fi

NEXT_SNAP_ID=$(($SNAP_ID+1))

SNAP_DIR="${DISK_PATH}.snap"
SNAP_DIR_SHORT="${DISK_PATH_SHORT}.snap"

SNAP_PATH="${SNAP_DIR}/${NEXT_SNAP_ID}"
SNAP_PATH_SHORT="${SNAP_DIR_SHORT}/${NEXT_SNAP_ID}"

# virsh snapshot-create by default creates snapshots for all the disks that
# are not read only. To be able to make a snapshot in only one of the disks
# an xml must be created describing all of the disks and setting the value
# snapshot='no' to the disks that are not going to be snapshotted.

# <domainsnapshot>
#   <name>1</name>
#   <description>snap 1</description>
#   <disks>
#     <disk name='vda' snapshot='no'/>
#     <disk name='vdb'>
#       <source file='/var/lib/one/datastores/1/09eec196c67b38dea41048a628978600.snap/1'/>
#     </disk>
#     <disk name='vdc' snapshot='no'/>
#   </disks>
# </domainsnapshot>

DOC="
<domainsnapshot>
  <name>${DISK_ID}-${SNAP_ID}</name>
  <description>snap ${DISK_ID}-${SNAP_ID}</description>
  <disks>"

for disk in $ALL_DISKS; do
    if [ "$disk" = "$TARGET" ]; then
        DOC="$DOC
    <disk name='$disk' snapshot='external'>
      <source file='$SNAP_PATH'/>
    </disk>"
    else
        DOC="$DOC
    <disk name='$disk' snapshot='no'/>"
    fi
done

DOC="$DOC
  </disks>
</domainsnapshot>"

CMD=$(cat <<EOT
set -ex -o pipefail

mkdir -p "${SNAP_DIR}"

PREVIOUS_SNAP=\$(readlink $SYSTEM_DS_DISK_PATH)

# The file must be created beforehand or libvirt complains with
# "permission denied"
touch $SNAP_PATH

# Temporary xml file
FILENAME="/tmp/snapshot-$VMID-$DISK_ID-$SNAP_ID"
echo "$DOC" > \$FILENAME

if virsh -c $LIBVIRT_URI domfsfreeze $DEPLOY_ID ; then
    trap "virsh -c $LIBVIRT_URI domfsthaw $DEPLOY_ID" EXIT TERM INT HUP
fi

virsh -c $LIBVIRT_URI snapshot-create $DEPLOY_ID --disk-only --atomic \
    --xmlfile \$FILENAME

rm \${FILENAME}

qemu-img rebase -u -b "\${PREVIOUS_SNAP}" "${SNAP_PATH}"
ln -sf $SNAP_PATH_SHORT $SYSTEM_DS_DISK_PATH
EOT
)

ssh_exec_and_log "${SRC_HOST}" "${CMD}" \
                 "Error creating snapshot ${SNAP_PATH}"

